Previous treatment systems for phosphating objects require a plurality of working steps, in particular 7 working steps, and exhibit a plurality of different baths for this purpose. The object is here first placed in a first bath, in which a first liquid is provided for degreasing the object. After degreased, the object must be conveyed from the first bath and into a second bath. In the second bath, a rinsing liquid is provided for rinsing the object. After rinsing, the object is conveyed into a third bath. The third bath is filled with a salt acid/sulfuric acid mixture. After the salt acid/sulfuric acid treatment, the object is sequentially conveyed to two additional baths each filled with rinsing liquid in order to rinse the object. In addition, the object is conveyed into a bath for passivation after the last rinsing bath. After passivated, the object is phosphated and then conveyed to another location for drying. In such a system, the highly toxic and environmentally detrimental chemicals in the degreasing baths and in the treatment baths have to be completely replaced after approx. 6 to 8 weeks of production time, since the chemicals have been spent after this period, and accruing sludge must be removed from the baths. This results in a system shutdown and high replacement and disposal costs.
As evident, the systems known from prior art require a great deal of space on the one hand, since they have to provide six different baths, and very many different chemical substances in high quantities on the other. In addition, conveying the objects from one bath to the next takes a great deal of time, corresponding transport systems and operating personnel. Furthermore, the used chemicals are toxic and environmentally detrimental, e.g., since sulfuric acids and salt acids are used, which either requires that expensive safety measures be implemented, or poses a high risk to the personnel and environment, as well as to the usually steel support structure.
Another objective is to prevent hydrogen embrittlement of the treated workpieces or objects to be treated. Hydrogen embrittlement normally results from hydrogen penetrating into and becoming embedded in a metal grid, and may lead to material fatigue. Hydrogen embrittlement is encountered when atomic hydrogen arises on the metal surface, either through hydrogen corrosion or in some other chemical reaction during metal treatment in which hydrogen participates, and is bound to the material more rapidly than it combines into non-diffusible H2 molecules on the material surface. A portion of the hydrogen is here embedded in the metal grid or deposited on defects or the grain boundary. Depending on the stress placed on the respective object, e.g., by introducing tensile residual stresses or loads, there exists a risk of material failure.